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36 terms

Chapter 17 Weather Patterns

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air mass
a huge body of air that has similar temp, pressure, and humidity at any given height; classified by temp and humidity
tropical
warm air masses that form in the tropics and have low air pressure
polar
cold air masses that form at high latitudes towards poles
maritime
air masses that form over oceans
continental
air masses that form over land and are dry
maritime tropical
form in gulf of mexico or over pacific ocean
maritime polar
form over north pacific and atlantic oceans; bring cool humid air
continental tropical
form over dry areas of southwest and northern mexico; bring hot dry weather- southern great plains
continental polar
form over central and northern canada and alaska, near arctic circle; bring clear, cold, dry air to north america (alberta clipper)
front
boundary between 2 air masses
cold front
a fast moving cold air mass overtakes a warm air mass; rising warm air cools, clouds forms; may bring heavy storms followed by cooler, drier air and clear skies
warm front
a warm air mass overtakes a slow moving cold air mass; warm air moves over cold air; may cause several days of precipitation followed by warm and humid air
stationary fronts
cold and warm air masses meet, but neither can move the other; water vapor in the warm air condenses into rain, snow, fog, or clouds; if stalled, may bring days of clouds and precipitation
occluded front
a warm air mass is caught between 2 cooler air masses; cool air flows under warm; as warm air cools and its water vapor condenses, the weather may turn cloudy and rain or snow may fall (weather cloudy and wet)
cyclone
swirling center of low air pressure; winds spin counterclockwise inwards towards center; bring clouds, wind, precipitation
anticyclone
swirling center of high air pressure; winds spin clockwise, outward from center; brings dry clear weather
storm
a violent disturbance in the atmosphere; sudden changes in air pressure, causes rapid air movement
thunderstorm
a small storm often accompianed by heavy precipitation and frequent thunder and lightning; form in large cumulonimbus clouds called thunderheads
lightning
a sudden spark or electrical discharge, as these changes jump between parts of a cloud, between nearby clouds, or between a cloud and the ground
thunder
the sound of the explosion from when the air expands because of lightning
Thunderstorm safety
____________: avoid places where lightning can strike and objects that conduct electricity
tornado
a rapidly whirling, funnel-shaped cloud that reaches down from a storm cloud to reach earth's surface
Tornado safety
_______________: a storm shelter on the basement of a well-built building is the best place for protection; stay away from windows and doors, lie under a sturdy object; if outside-lie in ditch
hurricane
a tropical cyclone that has winds of 119km per hour or higher; form in atlantic pacific indian oceans
how hurricanes form
begins over warm ocean water as a low pressure area, or tropical disturbance; if tropical disturbance grows in size and strength, it becomes a tropical storm hurricane
Hurricane safety
_____________: evacuate
hurricane watch
hurricane conditions are possible in the next 36 hours
hurricane warning
hurricane conditions are expected in the next 24 hours
blizzard
severe snowstorms, accompanied by high winds, low temps, low visibility
Blizzard safety
_____________: seek shelter, cover exposed parts of body, stay dry, car- keep exaust pipe clear
meteorologists
scientists who study the causes of weather and try to predict it- use maps, charts, and computers to analyze data and make forecasts
weather balloon
carries an instrument high into the troposphere and lower stratosphere to measure temp, air pressure and humidity
satellites
orbit in exosphere; make images of earth's surface, clouds, storms, snow cover
weather maps
shows location of fronts and areas of high and low pressure
isobars
lines joining points of equal pressure
isotherms
lines joining points of equal temperature